Computers and other electronic devices typically include a number of interconnected semiconductor devices. The semiconductor devices include a semiconductor chip or die containing internal circuitry. The dies are generally mounted in a package and connected to other semiconductor devices through external pins or contacts. However, the dies may also be connected directly to other circuitry, including another semiconductor die.
FIG. 1A is a side elevation view of a portion of a semiconductor die 20 having two bond pads 21 (shown as 21a and 21b) on a surface of the die. The bond pads 21 may be coupled to each other with circuitry 53 that is internal to the semiconductor die 20, as shown schematically in FIG. 1A. One bond pad 21a is electrically coupled with a wire 50 to a lead finger 43 of a conductive lead frame 40. In one conventional arrangement, one end of the wire 50 is bonded to the bond pad 21a with a "ball bond" 60 and the other end of the wire 50 is bonded to the lead finger 43 with a "wedge bond" 70. The semiconductor die 20 and the lead frame 40 may then be encapsulated in a plastic material (not shown) and ends 42 of adjacent lead fingers 43 (one of which is shown in FIG. 1A) may be bent downward to form connection pins. The pins may be inserted into corresponding sockets of another device (not shown) to couple the semiconductor die with the other device.
FIG. 1B is an enlarged side elevation view of a portion of the semiconductor die 20 shown in FIG. 1A, as the wire 50 is being attached to the bond pad 21a. The wire 50 can be attached with a wire bonding tool 30 (shown in FIG. 1B as a ball/wedge bonder 30a) by feeding the wire 50 downwardly through an aperture 31 of the ball/wedge bonder 30a and forming a wire ball 51 at the end of the wire 50. The ball/wedge bonder 30a then presses the wire ball 51 against the bond pad 21a while the remainder of the wire 50 extends approximately normal to the bond pad 21a. The bonder 30a then applies heat and/or pressure to the wire 50 at the wire ball 51 to bond the wire to the bond pad 21a, forming the ball bond 60 shown in FIG. 1A. For example, the bonder 30a can use a thermosonic or thermocompression process to apply both heat and pressure to the wire 50. The bonder 30a then moves along the wire 50 to the lead finger 43 and presses the wire 50 against the lead finger 43. The bonder again applies heat and/or pressure to the wire 50 to both bond the wire 50 to the lead frame 40 (forming the wedge bond 70 shown in FIG. 1A), and separate the bonded portion of the wire 50 from a remaining portion of the wire.
FIG. 2A is a side elevation view of the semiconductor die 20 having the wire 50 connected between the bond pad 21a and the lead finger 43 in accordance with another conventional arrangement in which a first wedge bond 70a is formed at the bond pad 21a and a second wedge bond 70b is formed at the lead finger 43. FIG. 2B is an enlarged side elevation view of a portion of the semiconductor die 20 shown in FIG. 2A as the wire 50 is being attached to the bond pad 21a.
Referring to FIG. 2B, the wire 50 can be attached to the bond pad 21a with a wedge/wedge bonder 30b by feeding the wire 50 through an aperture 31a of the wedge/wedge bonder 30b and pressing the wire 50 against the bond pad 21a. The wedge/wedge bonder 30b then applies heat and/or pressure to the wire 50 to bond the wire to the bond pad 21a, forming the first wedge bond 70a shown in FIG. 2A. The bonder 30b then moves along the wire 50 to the lead finger 43 and presses the wire against the lead finger 43. The bonder 30b again applies heat and/or pressure to the wire to bond the wire 50 to the lead finger 43, forming the second wedge bond 70b shown in FIG. 2A. In one conventional arrangement, the bonder 30b can apply sufficient heat and/or pressure to both bond the wire 50 to the lead frame 40 and separate the bonded wire from the remaining supply of wire. In another conventional arrangement, the bonded wire can be separated from the remaining wire by clipping the wire next to the second wedge bond 70b.
As discussed above, two or more bond pads 21 may be connected within the die 20 by internal circuitry 53. The internal circuitry 53 may include very small conductive lines. One drawback with this arrangement is that the conductive lines may have a high resistance, increasing the current necessary to transmit signals between the bond pads, and increasing the heat generated by each semiconductor die. In addition, internal circuitry 53 is inaccessible once the die has been manufactured. Accordingly, another drawback with conventional arrangements is that they may lack the flexibility for interconnecting bond pads that are not connected by the internal circuitry at the time of manufacture.
Yet a further drawback with the conventional methods and devices discussed above is that it may be difficult to route wires between the lead frame 40 and bond pads that are not proximate to the lead frame 40. For example, if one or more of the wires 50 is particularly long, so as to reach a particular bond pad, the wire may be more likely to break or contact other adjacent wires, creating a short circuit that can affect the operation of the semiconductor device.